President Trump stepped up his unrelenting Twitter rant at former FBI director James Comey on Sunday, accusing him of "many lies" and dismissing the one-time federal prosecutor as the "WORST FBI director in history, by far!"

The attacks come hours before Comey's interview with ABC's George Stephanopoulos was scheduled to air Sunday night. The network has been promoting the interview with enticing bits of information, including Stephanopoulos revealing that Comey compares Trump to a “mob boss.”

Comey is promoting his new book to be released this week, Higher Loyalty: Truth, Lies, and Leadership. Leaked excerpts have detailed Comey's mistrust of Trump, whom he describes as "ego driven" and "untethered to truth."

"I never asked Comey for Personal Loyalty," Trump tweeted. "I hardly even knew this guy. Just another of his many lies. His “memos” are self serving and FAKE!"

Trump ripped Comey for acknowledging Democratic candidate Hillary Clinton's lead in the 2016 presidential polls was a factor in how he handled the controversial Clinton email inquiry. Comey announced weeks before the election that he would not recommend charges be filed for Clinton's handling of emails while secretary of State.

Days before the election, however, Comey acknowledged that he was reviewing additional information in the case.

“In other words, he was making decisions based on the fact that he thought she was going to win, and he wanted a job," Trump tweeted. "Slimeball!”

Former New Jersey governor Chris Christie chimed in, tweeting that when he worked for Comey, "if I had told him 11 days before an election that I was releasing information that could effect an election, and the decision was influenced by polling, he would have fired me. He would have fired me on the spot.

"He is guilty of doing that himself-Wow"

Trump abruptly fired Comey in May, and Trump's tweet summarizing his overall perspective on Comey comes as no surprise: "Slippery James Comey, a man who always ends up badly and out of whack (he is not smart!), will go down as the WORST FBI Director in history, by far!"

The attack on Twitter was essentially a continuation of Trump's tweets Friday, when he called Comey "a proven LEAKER & LIAR" and a "untruthful slime ball."

Slippery James Comey, a man who always ends up badly and out of whack (he is not smart!), will go down as the WORST FBI Director in history, by far!

"Virtually everyone in Washington thought he should be fired for the terrible job he did-until he was, in fact, fired," Trump tweeted Friday.

White House spokeswoman Sarah Sanders also took on Comey on Sunday during an appearance on ABC's This Week.

"Look, it's been very clear that James Comey is a self-admitted leaker," Sanders said. "He lied to Congress. He's been inconsistent."

House Speaker Paul Ryan was somewhat more supportive of Comey, telling NBC's Meet the Press that Comey appeared to be a person of integrity. Ryan said, however, he had met Comey only a few times.

"I'm not going to try and help sell some books here," Ryan said. "I don't want to ... join some food fight, some book-selling food fight."

Former FBI director James Comey: A look at his career

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Comey testifies during the Senate Intelligence Committee hearing on June 8, 2017.

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Comey is sworn in during the Senate Intelligence Committee hearing on Capitol Hill on June 8, 2017.

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James Comey arrives before testifying in front of the Senate Intelligence Committee on June 8, 2017.

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Comey walks at his home in McLean, Va., on May 10, 2017, a day after being fired by President Trump.

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Comey testifies before the Senate Judiciary Committee on Capitol Hill on May 3, 2017.

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Comey listens to Attorney General Jeff Sessions speak about organized gang violence at the Department of Justice on April 18, 2017, in Washington.

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Comey delivers the keynote remarks at the Intelligence and National Security Alliance Leadership Dinner on March 29, 2017 in Alexandria, Va.

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Comey arrives to speak on national security challenges at the University of Texas on March 23, 2017, in Austin, Texas.

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Comey and National Security Agency Director Mike Rogers testify during a House Intelligence Committee hearing concerning Russian meddling in the 2016 election on March 20, 2017.

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Comey and National Security Agency Director Mike Rogers arrive to speak during the House Intelligence Committee hearing on Russian actions during the 2016 campaign on March 20, 2017, on Capitol Hill.

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Comey leaves a closed-door meeting with senators at the U.S. Capitol on March 15, 2017.

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Trump shakes hands with Comey during an Inaugural Law Enforcement Officers and First Responders Reception in the Blue Room of the White House on Jan. 22, 2017.

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Comey is sworn in on Capitol Hill on July 7, 2016, prior to testifying before the House Oversight and Government Reform Committee hearing to explain his agency's recommendation to not prosecute Hillary Clinton over her private email setup.

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Comey makes a statement at FBI headquarters in Washington on July 5, 2016, to announce that the agency would not recommend criminal charges in its investigation into Hillary Clinton's use of a private email server while serving as secretary of State.

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Comey listens to President Obama speak to members of the media in the Oval Office on June 13, 2016.

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Comey speaks about the FBI's request to Apple to unlock the iPhone of the San Bernardino shooter during a hearing before the House Intelligence Committee on Feb. 25, 2016.

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Comey prepares to testify on Capitol Hill on Dec. 9, 2015, before the Senate Judiciary Committee hearing on oversight of the FBI.

Comey speaks alongside Health and Human Services Secretary Sylvia Mathews Burwell about a national effort to crack down on Medicare fraud during a press conference at the Department of Justice on June 18, 2015, in Washington.

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Comey testifies at the Senate Appropriations Subcommittee on Commerce, Justice, Science and Related Agencies hearing on the proposed budget estimates for FY2016 on Capitol Hill on March 12, 2015.

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Comey speaks about the impact of technology on law enforcement on Oct. 16, 2014, at Brookings Institution in Washington.

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Comey, alongside Homeland Security Secretary Jeh Johnson and National Counterterrorism Center Director Matthew Olsen, testifies before the House Homeland Security during a hearing on Capitol Hill on Sept. 17, 2014.

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Comey speaks during a news conference on child sex trafficking at the FBI headquarters in Washington on June 23, 2014.

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Comey talks to reporters during a news conference in Sacramento, Calif., on Oct. 31, 2013.

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Comey talks with outgoing FBI Director Robert Mueller before being officially sworn in at the Justice Department in Washington on Sept. 4, 2013.

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Comey prepares for his Senate Judiciary Committee confirmation hearing on Capitol Hill on July 9, 2013.

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President Obama speaks during a news conference to announce his nomination of Comey to be FBI director in the Rose Garden on June 21, 2013.

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Comey testifies during a hearing before the House Judiciary Subcommittee
on Commercial and Administrative Law on May 3, 2007, on Capitol Hill.

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Comey announces federal grand jury indictments for three British nationals during a news conference on April 12, 2005, in Washington.

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Comey, then the U.S. attorney for the Southern District of New York, fields questions from the media on July 31, 2002.